CDA Workshop Physical & Numerical Hydraulic Modelling STAR-CCM+ - PowerPoint PPT Presentation

CDA Workshop Physical & Numerical Hydraulic Modelling STAR-CCM+ Presentation

CFD ENGINEERING FEA SIMULATION

Mission Increase the competitiveness of companies through optimization of their product development using engineering simulation.

Lx Sim Services – Engineering Simulation Outsourcing – CAE-Intensive Product Design – Training 4

Softwares • CFD • Optimization/DOE – STAR-CCM+ • OptiStruct – AcuSolve • HyperStudy • FEA • Process – HyperMesh/RADIOSS • HyperForm – HyperCrash • HyperXtrude – DesignLife • Moldex 3D • MBD • Post-Processing – MotionSolve • FieldView (CFD) 5

Sample Projects • DFBI - CFD • Trim and Drag Prediction on Ship Hull 6

Sample Projects • Non-Linear FEA • Prediction of Plastic Deformations on Frame 7

Sample Projects • Heat Transfer / Solar Radiation / Porous Baffle – CFD Automation of Solar Air Heater CFD • 8

Outline • STAR-CCM+ Overview and Capabilities • Modeling and simulation procedure • Limitations and known problems • Case Study • Questions 9

STAR-CCM+ Overview & Capabilities • CD-adapco is the largest privately owned CFD company • STAR-CCM+ GUI is java based, code is C++ – Very flexible – Customization possible – Java macro system • Finite volume method 10

STAR-CCM+ Overview & Capabilities • General purpose CFD – Multi-Physics • CAD package • Multiple meshing approaches • Included post-processing • Optimization 11

Complete Solution from CAD to Post 12

GUI Presentation • Tree-based management • Graphical window • Output • Properties 13

Tree-Based Management 14

CAD Preparation 3D-CAD • – Creating or modifying geometries – Similar to any sketch based package – Somewhat limited – Exposing design variables Operation History • – Boolean – Meshes – Adds repeatability 15

Wrapper and Surface Repair Before After 16

Meshers Trimmed cell • Polyhedral • – Embedded thin Tetrahedral • Prism • Thin mesher • Refinement • – Volume – Surfaces – Edges 17

Physics – Electrochemistry – Multiphase – Electromagnetism • Lagrangian – Overset meshes • Eulerian – Radiation • VOF – Aeroacoustics • DEM – Batteries – Conjugated heat transfer – Casting – Shell modeling – DFBI – Chemistry – FSI • Combustion • Solid stress • DARS • Direct coupling – Optimization solver – Adjoint solver 18

DAM Related Models • VOF for multiphase - Cavitation - Particle transport and interaction DEM - Erosion model • Moving parts, rotation, translation • Multiple meshes approach 19

Cons • No aeration by default or custom - Surface data not accessible during calculations • Babysitting necessary – Tweaking of interface solvers – Mesh dependency - Large mesh - Long transient analysis 20

Case Study – Modelling Method 21

Geometry Preparation • Create top boundaries • Operations to split in 3 regions – Inlet – Spillway – Outlet 22

Meshing • Trimmed cells – Known surface – Fast • Mesh alignment • Y+ between 10 and 150 targeted • Refinement for interface • Final mesh: – Convergence not fully obtained – Constraint in time and CPUs • Use of relative to base size values 23

Mesh - 0.52Hd - 2.7M Base size at 15m • Medium transition in • volume Surface • 0.375m in inlet and • outlet regions 0.15 m in spillway • 24

Mesh - 0.52Hd - 4.4 M Base size at 15m • Medium transition in • volume Surface • 0.375m in inlet and • outlet regions 0.15 m in spillway • 25

Physics Model • VOF multiphase • Turbulent – All y+ treatment • Transient analysis • Use of VOF wave to specify reservoir levels and inlets 26

Initial Conditions 27

Boundary Conditions Pressure VOFWave 28

Solver Set-Up and Convergence Multiple mesh approach to save computation time • Time step 0.01s to 0.05s • – Settings available to increase accuracy for C >1 – Stability issue 5 iterations per time step • Presence of oscillations in solution flow rate • – Potential mesh vs timestep problem – Choice made for time constraints vs accuracy 29

Case Study 1.5 X Design Head • Q = 601 m 3 /s • Maximum elevation at 224.2 m 30

Velocity 31

Velocity 32

Relative Pressure 33

Relative Pressure 34

Froude Number 35

Turbulent Kinetic Energy Generating Air Entrainment 36

Air Entrainment at Surface Only • Creation of field functions to find location air entrainment • Exportation of the approximate surface • Importation of the surface as a fluid region • Interpolate functions on it • Calculate aeration • Attempted transport without success 37

Air Entrainment at Surface Only 38

Case Study 0.52 X Design Head • Q = 115 m 3 /s 39

Velocity 40

Velocity 41

Relative Pressure 42

Relative Pressure 43

Froude Number 44

Turbulent Kinetic Energy Generating Air Entrainment 45

Air Entrainment at Surface Only 46

Questions?

Wrong BC??